Little Giant 1000 lb Capacity Steel Wagon Cart - 24W x 36L inch Deck

What's the difference between semi-pneumatic and pneumatic wheels?

Semi-Pneumatic Wheel - Semi-pneumatic tires and inserts feature molded-in air pockets, much like the air pockets in the soles of athletic shoes, providing a slightly cushioned ride. Found in forms ranging from poly urethane tires to inserts, semi-pneumatic tires never need air maintenance, nor will they become flat when punctured, making them truly flat-free. The important distinction, however, is that while all semi-pneumatic tires are flat-free, not all flat-free tires are semi-pneumatic, as with solid rubber tires or the carefree tires, which require no air in them. Load capacity max of about 350 to 400 lbs.

Pneumatic Wheel - Air-filled tires are known as pneumatic tires. The air compresses as the wheel goes over a bump or a load is applied to the cart and acts as a shock absorber. The tires are inflated through a valve and a drawback to this type of tire is that they can experience "flats." The advantage to this tire is a smoother more cushioned ride and some advantage to vehicle maneuverability. Pneumatic wheels are greatly affected by temperatures just like an automobile tire. A load capacity of about 350 - 400 lbs.